package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;

import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *

 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
        //缓存穿透
        Shop shop = cacheClient
                .queryWithPassThrough
                        (CACHE_SHOP_KEY,id,Shop.class,id2 -> getById(id2),CACHE_SHOP_TTL,TimeUnit.MINUTES);


        //1、互斥锁解决缓存击穿
        // Shop shop = queryWithMutex(id);
        //2、逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
        if (shop == null){
            return Result.fail("商铺信息不存在！");
        }

        return Result.ok(shop);
    }


    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期 --解决缓存击穿
     * @param id
     * @return
     */
    public Shop queryWithLogicalExpire(Long id){
        //1、从redis缓存中查询数据
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、存在 --直接返回
        if (StrUtil.isBlank(shopJson)){

            return null;
        }
        //3.1、命中，先将json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        //3.2、判断有没有过期
        if(expireTime.isAfter(LocalDateTime.now())){
            //3.3、未过期 , 直接返回旧的店铺信息
            return shop;
        }

        //3.4已过期需要缓存重建
        //4获取互斥锁
        String lockKey = LOCK_SHOP_KEY +id;
        boolean islock = tryLock(lockKey);
        //4.2、判读是否获取锁成功
        if (islock){
            try {
                CACHE_REBUILD_EXECUTOR.submit(() ->{
                    this.saveShopToRedis(id,20l);
                });
            } catch (Exception e) {
                throw new RuntimeException(e);
            }finally {
                unLock(lockKey);
            }
        }

        // ----返回过期的商铺信息
        return shop;


    }

    /**
     * 写一个逻辑缓存到redis
     * @param id
     * @param expireSecond
     */
    public void saveShopToRedis(Long id ,Long expireSecond){
        Shop shop = getById(id);

        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSecond));


        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY +id,JSONUtil.toJsonStr(redisData));

    }



    /**
     * 获取锁
     * @param key
     * @return
     */
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", LOCK_SHOP_TTL, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    /**
     * 互斥锁
     * @param id
     * @return
     */
    public Shop queryWithMutex(Long id){
        //1、从redis缓存中查询数据
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、存在 --直接返回
        if (StrUtil.isNotBlank(shopJson)){
            //存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //判断是否为空值
        if (shopJson != null){
            return null;
        }

        //3、不存在 --去数据库中查询
        //查询数据库之前， 先尝试获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean tryLock = tryLock(lockKey);
        Shop shop = null;

        try {
            //获取失败
            if (!tryLock){
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //获取成功

            shop = getById(id);
            //4、数据库中是否存在

            //5、不存在 ----返回404
            if (shop == null){
                //将空值写入 redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //6、存在 ---写入redis缓存中
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //释放互踩锁
            unLock(lockKey);
        }



        //7、返回shop
        return shop;
    }


    /**
     * 解决缓存穿透问题
     * @param id
     * @return
     */
    public Shop queryWithPassThrough(Long id){
        //1、从redis缓存中查询数据
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2、存在 --直接返回
        if (StrUtil.isNotBlank(shopJson)){
            //存在
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            //return Result.ok(shop);
            return shop;
        }
        //判断是否为空值
        if (shopJson != null){
//            return Result.fail("店铺信息不存在！");
            return null;
        }

        //3、不存在 --去数据库中查询
        Shop shop = getById(id);
        //4、数据库中是否存在

        //5、不存在 ----返回404
        if (shop == null){
            //将空值写入 redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
//            return Result.fail("店铺不存在！");
            return null;
        }
        //6、存在 ---写入redis缓存中
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7、返回shop

//        return Result.ok(shop);
        return shop;
    }

    /**
     * 更新数据库 ，删除缓存
     * @param shop
     * @return
     */
    @Override
    public Result upDate(Shop shop) {
        Long id = shop.getId();
        if (id== null){
            return Result.fail("店铺id不存在");
        }
        //1、更新
        updateById(shop);
        //2、删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY +shop.getId());
        return Result.ok();
    }


    /**
     * 按照地理坐标查询
     * @param typeId
     * @param current
     * @param x
     * @param y
     * @return
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        // 1.判断是否需要根据坐标查询
        if (x == null || y == null) {
            // 不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }



        // 2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        // 3.查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo() // GEOSEARCH key BYLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from) {
            // 没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });
        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        // 6.返回
        return Result.ok(shops);
    }
}
